A076378 n!-x!-1 is never prime for all x<n.

1, 2, 18, 19, 20, 24, 25, 27, 36, 39, 40, 41, 44, 46, 48, 51, 53, 57, 58, 60, 63, 69, 70, 72, 79, 80, 89, 96, 98, 107, 108, 111, 112, 114, 117, 118, 119, 120, 124, 127, 132, 134, 135, 139, 142, 144, 145, 150, 151, 152, 154, 160, 161, 169, 172, 176, 181, 183

Offset

1,2

Links

Table of n, a(n) for n=1..58.

Mathematica

nevpQ[n_]:=Module[{nf1=n!-1}, And@@(!PrimeQ[#]&)/@Table[nf1-x!, {x, n-1}]]; Select[Range[200], nevpQ] (* Harvey P. Dale, May 14 2011 *)

Prog

(PARI) for (a=1, 100, c=0; for (b=1, a-1, if (b%2<>a%2, continue); if (isprime(a!-b!-1), c=1; break)); if (c==0, print1(a, ", ")))

Crossrefs

Cf. A076379.

Sequence in context: A366950 A144158 A083502 * A231502 A231864 A066242

Adjacent sequences: A076375 A076376 A076377 * A076379 A076380 A076381

Keyword

nonn

Author

Jon Perry, Oct 08 2002

Extensions

More terms from Harvey P. Dale, May 14 2011.

Status

approved